在Javascript对象中var vs this [英] var vs this in Javascript object

问题描述

我正在为node.js开发一个web框架。这是代码;

I'm developing a web framework for node.js. here is the code;

function Router(request, response) {
        this.routes = {};

        var parse = require('url').parse;

        var path = parse(request.url).pathname,
            reqRoutes = this.routes[request.method],
            reqRoutesLen = reqRoutes.length;

        ..... // more code

};

我应该将所有var更改为此，如下所示：

Should I change all the var to this, like so:

function Router(request, response) {
        this.routes = {};

        this.parse = require('url').parse;

        this.path = this.parse(request.url).pathname;
        this.reqRoutes = this.routes[request.method];
        this.reqRoutesLen = this.reqRoutes.length;

        ..... // more code

};

有任何意见吗？

推荐答案

如果希望属性在相关对象的生命周期中保持不变，则将属性添加到此。对局部变量使用 var 。

Add properties to this when you want the properties to persist with the life of the object in question. Use var for local variables.

编辑—正如Bergi在评论中指出的那样，用 var 声明的变量在从函数调用返回时不会必然消失。它们是，并且只能直接访问声明它们的范围内的代码，以及词汇嵌套的范围。

edit — as Bergi notes in a comment, variables declared with var don't necessarily vanish upon return from a function invocation. They are, and remain, directly accessible only to code in the scope in which they were declared, and in lexically nested scopes.

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